"No score" in cricket is unacceptable (3,2)
I believe the answer is:
not on
'unacceptable' is the definition.
(something 'not on' is unacceptable or frowned upon)
'no score in cricket' is the wordplay.
'score in cricket' becomes 'ton' (I can't explain this - if you can you should believe this answer much more).
'no'+'ton'='NOT ON'
'is' is the link.
Can you help me to learn more?
(Other definitions for not on that I've seen before include "Common expression meaning won't be entertained or tolerated" , "Informally, cannot be permitted or tolerated" , "Unacceptable (colloq.)" , "Improper - impossible" , "Colloquially, cannot be tolerated or accepted" .)